Zirconium carbon getter member

ABSTRACT

A getter member comprised of an open-ended container composed for example of molybdenum or carbon, having a sintered porous mass composed of a mixture of zirconium and up to about 30 percent by weight carbon therein. The getter member is nonevaporable and operable at room temperatures so as to be positionable at any desired location within an electric discharge tube. Means for securing the getter material within its container is also disclosed.

States Patent 191 11] 3,820,919 June 28, 1974 [73] Assignee: SiemensAktiengesellschaft, Berlin,

Munich, Germany 22 Filed: Dec. 13, 1971 21 Appl. No.: 207,022

[30] Foreign Application Priority Data Dec 21, 1970 Germany 2062992 [52]US. Cl. 417/48, 252/1816 [51 int. Cl. F04b 37/00 [58] Field of Search252/1816; 313/174, 176, 313/178; 417/48, 49, 51

[56] References Cited UNITED STATES PATENTS 1,733,809 10/1929 Ledereru,417/51 X 2,043,724 6/1936 Anderson i i 417/48 2,167,852 8/1939 Rose417/48 2,175,695 10/1939 Kniepen l i 252/1816 2,208,692 7/1940 Wamsley417/48 2,824,640 2/1958 Della Porta 417/48 2,855,368 10/1958 Perdijk252/1816 3,102,633 9/1963 Baronetzky... 417/51 3,225,910 12/1965 DellaPorta 417/48 3,428,168 2/1969 Reash 417/51 3,560,788 2/1971 Reash 417/513,584,253 6/1971 Wintzer 417/51 Primary Examiner-William L. FreehAttorney, Agent, or FirmHill, Gross, Simpson, Van Santen, Steadman,Chiara & Simpson '[5 7 ABSTRACT A getter member comprised of anopen-ended container composed for example of molybdenum or carbon,having a sint'ered porous mass composed of a mixture of zirconium and upto about 30 percent by weight carbon therein. The getter member isnonevaporable and operable at room temperatures so as to be positionableat any desired location within an electric discharge tube. Means forsecuring the getter material within its container is also disclosed.

1 Claim, 9 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of theInvention The invention relates to getters and more particularly togetter members operable at room temperatures in electric dischargetubes.

2. Prior Art It is known to completely enclose vaporizable gettermaterials within a container and position the same within an electricdischarge tube so that a getter material mirror-like film is produced onthe envelope of the tube, as by HF annealing. A serious drawback withsuch vaporizable getter materials is that it is difficult to control thegetter material vapors and it is extremely important to avoid depositinggetter material film on any important parts of a discharge tube,particularly on any insulating parts thereof.

Such drawbacks are substantially eliminated with non-evaporating gettermaterials, however, nonevaporating getter materials must be heated,either temporarily, repeatedly or continuously, within the dischargetube by special heating devices thereby rendering such gettersuneconomical.

The invention provides non-evaporating getter members that substantiallyeliminate the prior art drawbacks.

SUMMARY OF THE INVENTION The invention provides non-evaporating gettermembers comprised of substantially open-ended container of molybdenum orcarbon having a porous sintered getter material therein comprised of amixture of zirconium and up to about 30 percent carbon. The gettermembers of the invention are operable at room temperatures and areattached to a desired position of an electric discharge tube withoutheating devices. The adhesion between the container and the gettermaterial is sufficiently great so that as a general matter, no specialsecurement is required to insure retention of the getter material withinthe container. However, with particularly valuable tubes, suchsecurement is reassuring. Accordingly, certain embodiments of theinvention include means of securing the getter material within thecontainer, such as wires, cap-like structures, shaped bars or similarmembers attached to the container and holding the getter materialtherein. The securing means can be attached to the container andsintered in with the getter material or be attached after the gettermaterial has been sintered.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevated sectional viewof an embodiment constructed in accordance with the principles of theinvention;

FIG. 2 is a somewhat similar view of another embodiment of theinvention;

FIG. 3 is also a similar view of yet another embodiment of theinvention;

FIG. 4 is a similar view of a further embodiment of the invention;

FIG. 5 is a partial elevated sectional view of another embodiment of theinvention;

FIG. 6 is a view somewhat similar to FIG. 5 of a further embodiment ofthe invention;

FIG. 7 is an elevated sectional view of a further embodiment of theinvention;

FIG. 8 is a somewhat similar view of a modified form of the inventionillustrated at FIG. 7; and

FIG. 9 is a partial elevated sectional view of another embodiment of theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention provides gettermembers operable at room temperatures in electric discharge tubes or thelike wherein the getter material is positioned within a substantiallyopen-ended container, for example, in an open-ended recess of asheet-metal container that is readily securable to operating portions orto other portions of an electric discharge tube. The nonevaporatinggetter material of the invention is comprised of a mixture of zirconiumand up to about 30 percent by weight carbon (graphite) sintered into ahighly porous mass. The container is composed of relatively hightemperature resistant material, such as molybdenum or carbon and isattachable at a desired position within an electric discharge tube.Heating devices are not necessary for the getter members of theinvention.

The adhesion between the-container and the getter material mass is of asufficient-strength so that generally no securing means therebetween isrequired. However, when the getter member of the invention is utilizedin a particularly valuable discharge tube, various types of securingmeans are provided to prevent the getter material mass from falling outof the container.

The securing means include wires, sheet-caps, rods, Z-shaped orU-'shaped bars as well as other similar structures generally composed ofmolybdenum, tantalum or other similar metals. The securing means areattached to the container by various means, such as spotwelding,crimping, passing through portions thereof, etc., and are attached tothe getter material by being embedded therein or by contacting a surfaceportion thereof. The securing means are attached to the getter materialeither prior to the sintering process and sintered in with the gettermaterial or are suitably attached after the sintering process.

The invention results from systematic investigations withzirconium-carbon mixtures conventionally applied to arrangements thatare adapted for periodic, repeated or continuous heating, for example,as applied to a heating coil insulated with aluminum oxide. It wasdiscovered that a large getter capacity can be obtained from such amixture without heating. The zirconiumcarbon mixtures have gettercharacteristics, particularly when in a large pore sintered state, thatare suited for production of getter members operable at roomtemperatures. Such getter members are heated only once during theproduction of a particular discharge tube and are thereby freed of theirown gases to such a degree that they have a sufficiently large capacityfor additional gases, even in a cold state over extended periods oftime.

The range of composition of the zirconium-carbon mixture is relativelybroad and varies from about a minimum of percent by weight of zirconiumand a maximum of about 30 percent carbon. The maximum amount ofzirconium in the mixture is about to percent while the minimum amount ofcarbon in the mixture is about to percent. Accordingly, a preferred wayof expressing the composition of this mixture is to indicate that it iscomprised of a mixture of about 70 percent to 95 percent by weight ofzirconium and about 5 percent to 30 percent by weight of carbon.

The getter material of the invention have particularly good adhesivecharacteristics to the material of the container as well as to itself sothat no loose particles are present. Accordingly, a getter mass formedfrom such materials can be utilized as a relatively thick layer. Thegetter members of the invention having such relatively thick layers ofgetter material have a gas capacity, which even in a cold state exceedsthe gas capacity of presently known getters.

Referring now to the drawings, wherein like reference numerals referredto like elements, FIG. 1 illustrates a getter member embodimentcomprised of a container 1 composed for example of molybdenum, formedinto an open-ended body having an interior recess or the like. Asintered mass 2 composed of a mixture of zirconium and carbon ispositioned and tightly bonded to the interior recess of the container 1.

FIG. 2 illustrates a somewhat modified form of the getter memberembodiment discussed in FIG. 1, wherein one or more molybdenum wires 3are spotwelded onto the exterior portions of the container 1 so as toprevent the sintered mass 2 from falling out.

In a further modified form shown at FIG. 3, a molybdenum Z-shaped bar isspot-welded to the bottom of the interior recess of container 1 and thenembedded in the zirconium-carbon mixture and sintered in with the mass 2so as to secure the same from displacement.

FIG. 4 illustrates a further modified embodiment of a getter memberwherein a tantalum sheet or strip 5 is crimped onto the exterior flangesof the container 1 and extends over at least a portion of the openingthereof for maintaining the mass 2 in position.

FIGS. 5 and 6 illustrate cylindrical getter member embodiments wherein asheet-metal container 11, for example, formed of a high-temperatureresistant material such as molybdenum or carbon, is filled with azirconium-carbon mixture sintered into a highly porous mass 12. In orderto insure that the mass 12 does not become detached from its container,securing means are provided. In FIG. 5, such securing means comprise abent wall portion 14 of the container 11, while in FIG. 6, the securingmeans comprise a wire 13 attached to the interior of container 11 andembedded within the mass 12.

The embodiments illustrated at FIGS. 7, 8 and 9 are comprised of asubstantially open-ended carbon container 21, filled with a sinteredmass 22 of a zirconiumcarbon mixture. The adhesion between the carboncontainer 21 and the mass 22 is extremely good and very reliable duringoperation. Accordingly, the embodiment illustrated at FIG. 7 does notutilize any special securing means. In the embodiment illustrated atFIG. 8, a rod 23, as of molybdenum penetrates through opposing wallportions of the container 21 and through the mass 22 to insure that themass 22 does not become detached from the container. In the partial viewof the embodiment shown in FIG. 9, a U-shaped member 24 is inserted andpenetrates through opposed wall portions of container 21 and throughmass 22 so as to secure the same from displacement.

During production of the getter members of the invention a recess isformed, for example, in a thin molybdenum sheet by the application ofsuitable pressure. The formed recess is substantially completely filledwith a suitably formulated viscous zirconium-carbon mixture, as bysmearing. The getter member is then sintered. It is then ready forinsertion into a discharge tube, even a relatively small tube. Duringproduction of discharge tubes, they are heated, for example, by highfrequency (HF) and the getter material is freed of gas. In anotherembodiment, a relatively small tube or cylinder, for example ofmolybdenum, of a given diameter is formed and filled with azirconium-carbon mixture. The so-filled tube is then sintered andsuitably attached in a discharge tube. In embodiments wherein the gettermembers are of relatively large dimensions, it is useful in at leastcertain instances to provide securing means to insure that the gettermaterial does not separate from its container, as in the form of azirconium-carbon plug or the like.

Various changes and modifications to the above described embodiments ofthe invention may be made without departing from the spirit and scopethereof and is intended that all matters contained in the abovedescription shall be interpreted as illustrative and not as limiting.

I claim as my invention:

1. A getter member for operating at room temperature in an electricdischarge tube comprised of a container having a substantiallyopen-ended recess therein, said container being composed of a relativelyhightemperature resistant material selected from the group consisting ofmolybdenum and carbon, and a sintered porous non-evaporable getteringmass attached within said recess, said sintered porous gettering massbeing comprised of a mixture of about to percent by weight of zirconiumand about 5 to 30 percent by weight of carbon.

